240 CEMENT MATEEIALS AND INDUSTRY. [bull. 24 
I 
been bent into great folds, which originally formed a succession 
arches and troughs. During the enormously long period which h 
elapsed since the folding occurred, hundreds, perhaps thousands, 
feet of strata have been worn off from the arches, so that beds whic 
were once deep below the surface are now exposed to view. The ax^ 
of these folds extend in a northeast-southwest direction, so that th fl 
formations lie in long and comparatively narrow belts that extend j j 
the same direction. Along the central line of an upfold of the strati 
or anticline the older rock is exposed. The beds slant or dip aw 
from the axis, and younger and higher beds are found toward th 
flanks. The Kittatinny limestone, being older than the Trenton and 
Hudson, occurs along the central line of the anticlines. 
The reverse relations are true where the strata are downfolded, i. e. 
at the synclines. Here the younger beds are found along the medi 
line, toward which the strata dip, and the older beds are found on 
flanks. 
The simple structure of anticlinal and synclinal folds is often coflH 
plicated by faults or fractures, along which the strata have move 
past one another. The fault planes may be inclined at various angle 
and the motion may have been in any direction along them. Asl 
result of faulting a given bed may not appear at the surface, or it ma 
be repeated and form a double line of outcrops. Consequently th 
Trenton limestone does not occur everywhere between the outcrop 
slate and Kittatinny limestone where it is expected, and it sometime 
does occur apparently in the midst of the older limestone format! 
where it is not expected. Again for long intervals the rock ma} T t| 
buried beneath thick accumulations of glacial drift, which conceal it 
outcrop, but in these cases it can always be found by digging. 
LIMESTONES OF UPPER DELAWARE VALLEY. 
Limestones and calcareous shales of various kinds are found alon: 
Wallpack Ridge, from Tristates to Wallpack Bend, on Delaware Rivei 
With the exception of that part of the ridge near Tristates all thj 
area is so far removed from any railroad that for lack of transports 
tion facilities any deposits of cement rock and limestone within ] 
must remain undeveloped for many }^ears. For this reason these lime 
stones were not studied with the same care as those of f he KittatinH 
Valley. 
Doctor Cook published in 1868 analyses of specimens from varioi) 
horizons, which indicate that many of the beds have a high percentage 
of carbonate of lime, and are practically free from magnesia. Finelj 
ground and mixed with clay in the right proportion the}^ would mak 
good Portland cement, or the rock could be used to raise the percem|' 
age of lime in a cement rock deficient in it. These formations wei 
described by Mr. Weller in the annual report for 1899, pages 1-16. 
